Nickel oxide ores are composed of two kinds of minerals; one is saprolite that is processed by smelting to obtain nickel products, and the other is limonite that is used in hydrometallugical processes. It is not efficient economically to process the mixture of limonite and saprolite, so the processes to saparate the ore mixture should be developed. In the present study, the mixture was separated by dry-classification after liberationg using grindability difference between limonite and saprolite. Consequently, it is possible to obtain the limonite with less than 10% of Mg+Si contents, which could be treated by hydrometallurgical processes, when the limonite contain less than 30% of saprolite.